CIE A Level Chemistry (9701) 2019-2021

Revision Notes

7.6.1 Production of Amines

Production of Primary & Secondary Amines

  • Primary amines are organic compounds which have an amine (-NH2) functional group attached to an alkyl or aryl group
  • Examples of primary amines are ethylamine and phenylamine

Nitrogen Compounds - Ethylamine _ Phenylamine, downloadable AS & A Level Chemistry revision notes

Ethylamine and phenylamine are examples of primary amines

  • Primary amines, such as ethylamine, can be prepared from different reactions including:
    • The reaction of halogenoalkanes with ammonia
    • The reduction of amides
    • The reduction of nitriles
  • Phenylamine is prepared from the reduction of nitrobenzene with tin and concentrated HCl

Production of ethylamine

Reaction of halogenoalkanes with ammonia

  • This is a nucleophilic substitution reaction in which the nitrogen lone pair in ammonia acts as a nucleophile and replaces the halogen in the halogenoalkane
  • When a halogenoalkane is reacted with excess, hot ethanolic ammonia under pressure a primary amine is formed
    • Chloroethane and hot ethanolic ammonia react to form ethylamine

Nitrogen Compounds - Primary Amine Formation, downloadable AS & A Level Chemistry revision notes

Formation of ethylamine from chloroethane and ammonia

Reduction of amides

  • Amines can also be formed from the reduction of amides by LiAlH4 in dry ether
  • Whether a primary or secondary amine is formed depends on the nature of the amide
    • Ethanamide is reduced by LiAlH4 to form ethylamine

Nitrogen Compounds - Reduction of Amides to form Ethylamine, downloadable AS & A Level Chemistry revision notes

Ethylamine can also be formed by reducing ethanamide using LiAlH4

Reduction of nitriles

  • Nitriles contain a -CN functional group which can be reduced to an -NH2 group
  • The nitrile vapour and hydrogen gas are passed over a nickel catalyst
  • The nitrile can also directly react with the reducing agent LiAlH4 in dry ether to form a primary amine
    • Ethanenitrile gets reduced by H2/Ni or LiAlH4 to ethylamine

Nitrogen Compounds - Reduction of Nitriles, downloadable AS & A Level Chemistry revision notes

Reduction of ethanenitrile by LiAlH4 or H2 and Ni catalyst to form ethylamine

Production of phenylamine

  • Phenylamine is a primary amine consisting of a benzene ring and an amine functional group
  • It can be produced in a two-step synthesis reaction followed by the separation of phenylamine from the reaction mixture
    • Step 1: benzene undergoes nitration with concentrated nitric acid and concentrated sulfuric acid at 25 to 60 oC to form nitrobenzene
    • Step 2: nitrobenzene is reduced with hot tin (Sn) and concentrated hydrochloric acid under reflux to form an acidic mixture which contains the organic product C6H5N+H3
    • Step 3: sodium hydroxide (NaOH) is added to the acidic reaction mixture to form phenylamine
    • Step 4: the phenylamine is separated from the reaction mixture by steam distillation

Nitrogen Compounds - Preparation of Phenylamine Overall, downloadable AS & A Level Chemistry revision notes

Overall reaction of formation of phenylamine from benzene

Nitrogen Compounds - Preparation of Phenylamine (1), downloadable AS & A Level Chemistry revision notes

Nitrogen Compounds - Preparation of Phenylamine (2), downloadable AS & A Level Chemistry revision notes

Multi-step synthesis of phenylamine from benzene

Author: Francesca

Fran has taught A level Chemistry in the UK for over 10 years. As head of science, she used her passion for education to drive improvement for staff and students, supporting them to achieve their full potential. Fran has also co-written science textbooks and worked as an examiner for UK exam boards.
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